1. Field of Invention
This invention relates to plastic bags of the type commonly used for produce and breads. It is an improved closure for such bags, i.e., it is an improved device for holding the necks of such bags closed.
2. Description Of Prior Art
Produce markets commonly supply transparent polyethylene (poly) bags to shoppers for bagging and carrying home purchased items of produce, such as lettuce and apples. Also such bags are commonly used in factory packaging to provide a resealable outer covering for loaves of bread, as well as for other uses, including non-edibles as well as foods.
When orignally supplied at the factory, these bags were sealed with staples or by heat, but users objected to such methods of closure since they were of a "permanent" nature in that the bags could be opened only by tearing them, thereby rendering them impossible to reseal.
Thereafter several types of closures were provided to seal plastic bags in a way which left the bags undamaged after they were opened. U.S. Pat. No. 4,292,714 to Walker (1981) discloses a complex clamp which can close bag necks without damaging them. However these clamps are prohibitively expensive to manufacture for any mass-merchandising operation. U.S. Pat. No. 2,981,990 to Balderree (1961) shows a closure which is has two holes through which the bag's neck must be threaded and hence is difficult to manipulate, is relatively large, is expensive (it is made of PFTE), protrudes rather than lies flat when installed, and which is not useable unless the bag has a relatively long "neck" or twistable portion. Thus if a bag has a short neck due to a high degree of filling, the latter closure is useless.
Several types of thin, flat closures have been proposed, e.g., in U.K. Patent No. 883,771 to Britt et al. (1961), and in U.S. Pats. Nos. 3,164,250 (1965), 3,417,912 (1968), 3,82,441 (1974), 4,361,935 (1982), and 4,509,231 (1985) to Paxton. While inexpensive to make, useful for bags with a short neck portion, and supplyable in break-off strips, such closures can be used only once. This is because they are invariably made of frangible plastic, yet they must be bent or twisted to remove them. As a result of these two oposing factors, they fracture upon removal. Thus to reseal a bag originally sealed with a frangible closure, it must be resealed either by twisting its neck using a new closure, tying a knot in its neck, folding the neck under the bag so that the weight of the contents will hold the neck closed, or held closed with a twist-type (wire core) closure.
All of these methods of resealing have their disadvantages. The need for a new closure each time the bag is reclosed is very inconvenient. Knotting the neck is inconvenient and difficult to reverse if the knot becomes tight. Folding the neck under is useful only if the neck is long and is unreliable if the bag is moved or picked up since the neck can open and the contents can spill easily. Twist closures are time-consuming to use and become unsightly and inefficient after repeated use.